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Troubling chemicals detected in people
by Daniel P. Jones
Chemicals commonly used in everyday plastic products and beauty aids - everything from nail polish and perfume to garden hoses and food wrap - are being detected in people at levels that concern federal health experts.
The family of chemicals, called phthalates, includes some that can cause birth defects and disrupt hormonal functions, which control normal cell development and reproduction.
The safety of phthalates (pronounced tha-lates) already had been called into question last year when European countries banned their use in soft baby rattles and teething toys because the chemicals leach out of plastic. U.S. manufacturers voluntarily removed phthalates from those baby items in 1998.
But little was known about the extent to which phthalates were finding their way into human bodies. The chemicals are used in various kinds of plastics, such as polyvinyl chloride, to make products soft and flexible and in lubricants and cosmetics.
Two specific phthalates have received the most attention as potential health hazards. The chemicals - diisononyl phthalate, or DINP, and di (2-ethylhexyl) phthalate, or DEHP - were the ones used in baby products and are the phthalates produced in the largest quantities. Meanwhile, other phthalate compounds continue to be used in a host of items with little public scrutiny.
Now researchers at the federal Centers for Disease Control and Prevention (CDC) have tested urine samples from people across the country and found phthalates at "levels we are concerned about," said John Brock, a chemist at the CDC's National Environmental Health Center who leads the research team.
What worries researchers is that the phthalate levels discovered in people are much higher than levels of other well-studied pollutants routinely detected in people, such as polychlorinated biphenyls, or PCBs, which also are known to disrupt hormonal functions.
The findings are surprising. DEHP and DINP were not the ones found at the highest concentrations, according to scientists outside the CDC who are familiar with the research.
In addition, levels of phthalates detected in people "are higher than we anticipated," Brock said.
Brock said he could not divulge levels or specific phthalates detected because the information has not been released by the agency and published in a peer-reviewed journal. Brock declined to name the journal that is to publish the information, but researchers outside the CDC say it will appear in the October issue of Environmental Health Perspectives.
Scientists familiar with the CDC's work say that people should not panic and throw away products that contain or may contain phthalates. But, they add, the report is certain to broaden the debate over phthalates beyond baby products.
"It's going to rewrite how we look at phthalates," said Louis Guillette Jr., a University of Florida zoology professor who was on a National Academy of Sciences panel that studied hormone-disrupting contaminants, including phthalates.
"Phthalates have been something of concern up to this point," he said. "Basically, they're going to leap upward in terms of concern."
Because phthalates are used so widely, any call to label or reformulate hundreds of products would meet with stiff resistance from manufacturers. The American Council on Science and Health, supported by grants from corporations and foundations, contends that claims of harm from phthalates are exaggerated and that the chemicals are safe.
In its report last year, the National Academy panel said phthalates can cause health problems in humans and wildlife, including birth defects and reproductive disorders. The panel called for research on how such contaminants could be harming human health.
To begin answering that question, scientists must determine the levels and types of phthalates in people. The main way the chemicals enter the body is through food, experts say, though they also can be absorbed through the skin and inhaled. Some chemicals can pass from mother to fetus in the womb.
"I can tell you that we're going to be working on phthalates for a long time here at the CDC," Brock said.
Scientists and health experts familiar with phthalate research say they are eager to compare the levels of the chemicals the CDC detected in people with levels that have caused birth defects and reproductive disorders in laboratory experiments with rats.
In a series of separate studies over the past several years, researchers at the Environmental Protection Agency (EPA) and at the Chemical Industry Institute of Toxicology have fed high doses of phthalates - primarily di (n-butyl) phthalate, or DBP - to female rats and found that the chemical produces permanent defects in the reproductive systems and organs of the rats' male offspring.
"If you take the (CDC's human) exposure data, that these things are occurring at high concentrations, and you look at the experimental data on developing rats, you realize that the doses aren't that far apart," Guillette said. "The levels that we're measuring in people, and the (animal) studies we have about developmental effects raise concerns for me and for a lot of scientists in this field."
Earl Gray, an EPA research chemist and phthalate expert who has done some of the rat experiments, said one of his concerns is that tests that look at a chemical's potential effects on offspring are not required when chemicals are produced and used in industry.
"The types of tests we do are not routinely done," Gray said.
Some products are labeled as containing phthalates, but some are not, and manufacturers are not required to release that information, Gray said.
"A bigger issue is what are we exposing people to that we don't know about," he said.
Scientists have known for several years that phthalates were present in human blood serum and urine.
But most scientists until now assumed the phthalates were contaminants that found their way into samples from plastic laboratory equipment after the samples were drawn from people, Guillette said. Some scientists probably still assume that, he said.
In fact, Brock, who leads the research team at the CDC, was trying to devise better ways to detect and measure PCBs, DDT and other high-profile pollutants in people when he noticed contaminants in serum several years ago. He determined that the chemicals were phthalates, and subsequently was able to show that they were not the result of lab contamination but were in the human serum to begin with; the findings were published in a scientific journal in 1996.
Since then, Brock and his team spent more than four years developing a way to detect the metabolites of phthalates - the breakdown products not used in commercial industry but created only when they pass through a liver or kidney - instead of looking for the parent compounds.
"It's one thing to hypothesize risk, or guess at what we're exposed to.
It's another deal to actually measure what we're exposed to," Guillette
said. "If we want to know what public health risks exist, we need to measure